Roller bearing assembly

ABSTRACT

A roller bearing assembly including an tapered inner cup defining an inner raceway, an tapered outer cup defining an outer raceway, the outer raceway having a convex profile, the convex profile being defined by an intersection of the outer raceway and a central plane in which a longitudinal center axis of the roller bearing assembly lies, and a plurality of straight rollers disposed between the tapered inner cup and the tapered outer cup so that each straight roller is in rolling contact with the inner raceway and the outer raceway, each straight roller having a first end face, a second end face and a cylindrical body extending therebetween.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/522,942 filed Apr. 28, 2017, which is a 35 U.S.C. § 371 nationalstage application of PCT/US2014/063659, filed Nov. 3, 2014, the entiredisclosures of which are incorporated herein.

FIELD OF THE INVENTION

The present invention relates generally to roller bearing assemblies.More particularly, the present invention relates to a roller bearingassembly including straight rollers that can be utilized forapplications in which tapered roller bearing assemblies are often used.

BACKGROUND OF THE INVENTION

Various applications require roller bearing assemblies that can handleboth axial and radial loads. Typically, roller bearing assemblies usedin these applications include a plurality of tapered rollers disposedbetween a pair of inner and outer raceways, each of which iscorrespondingly angled, or tapered and meeting at an apex, with regardto a longitudinal center axis of the corresponding bearing assembly toallow for pure rolling. As such, these assemblies are commonly referredto as tapered roller bearing assemblies. Tapered rollers are larger atone end as opposed to the other, and include a body that extendstherebetween and is formed by a frustoconical outer surface. As well,the outer surface of a tapered roller's body may be profiled in variousapplications. As would be expected, such tapered rollers can bedifficult and time consuming to manufacture and, therefore, alsoexpensive to manufacture.

As such, it would be desirable to utilize a bearing assembly 10, such asthe one shown in FIG. 9 , that utilizes a plurality of straight rollers20, that are relatively easy to manufacture as compared to taperedrollers, and rotatably received in a roller retainer 17 between atapered inner cup 12 and a tapered outer cup 14 of the bearing assembly.As noted, inner cup 12 and outer cup 14 define an inner raceway 16 andouter raceway 18, respectively, both of which are defined byfrustoconical surfaces. Referring additionally to FIG. 10A, a portion offrustoconical outer raceway 18 is shown with a corresponding straightroller 20 when bearing assembly 10 is in the “at rest” position. Whenthe bearing assembly is “at rest,” meaning there is no relative rotationbetween its tapered inner cup 12 and tapered outer cup 14, each straightroller 20 may be in contact with both frustoconical inner raceway 16 andfrustoconical outer raceway 18 along the entire length of the roller, asa longitudinal center axis 24 of each straight roller 20 intersects alongitudinal center axis 24 of the bearing assembly.

Note, however, as relative rotation occurs between inner cup 12 andouter cup 14, each straight roller 20 will begin to rotate about itspivot axis 26 (FIG. 9 ) that is both transverse to its longitudinalcenter axis 24 and extends outwardly from its midpoint to intersectlongitudinal center axis 22 of the bearing assembly. This rotationalmotion about pivot axis 26 is driven by the tangential speeds of theroller's surfaces relative to their radial position on the inner andouter cups 12 and 14, as best seen in FIGS. 10B and 9 . Note, the fullextent to which each straight roller 20 may rotate about its pivot axis26 is limited by the dimensions of its corresponding retainer rollerpocket 23. Rotation of each straight roller 20 about its correspondingpivot axis 26 is due to the fact that its first end face 21 does nothave as far to travel along outer raceway 18 as does its second end face23. For example, as shown in FIG. 10B, for straight roller 20 not torotate about its pivot axis 26, second end face 23 would have to rollalong “fast path” 17 of raceway faster than first end face 21 rollsalong “slow path” 19 since fast path 17 is a larger circular path thanis slow path 19. Of course, this is not possible as all portions ofstraight roller 20 roll simultaneously. “Neutral path” 21 represents thepath that the midpoint of each straight roller 20 travels along outerraceway 18.

Referring now to FIGS. 10B and 12 , the rotation of straight roller 12about its pivot axis 26 causes frustoconical outer raceway 20 to nowfunction as though it has a concave profile with respect to longitudinalcenter axis 24 of the straight roller. This concave profile is ahyperbolic conic section as defined by the plane running throughlongitudinal center axis 24 of the rotated straight rollers 20 and thepoints where first and second end faces 21 and 23 of the rollers contactouter raceway 18. As shown, this configuration leads to undesirable endloading of straight rollers 20 and, therefore, undesirable stressprofiles for the straight rollers. Such end loading can lead to spallingand, ultimately, bearing failure within an unacceptable timeframe.

The present invention recognizes and addresses considerations of priorart constructions and methods.

SUMMARY OF THE INVENTION

One embodiment of a roller bearing assembly, in accordance with thepresent disclosure, includes a tapered inner cup defining an innerraceway, an tapered outer cup defining an outer raceway, the outerraceway having a convex profile, the convex profile being defined by anintersection of the outer raceway and a central plane in which alongitudinal center axis of the roller bearing assembly lies, and aplurality of straight rollers disposed between the tapered inner cup andthe tapered outer cup so that each straight roller is in rolling contactwith the inner raceway and the outer raceway, each straight rollerhaving a first end face, a second end face and a cylindrical bodyextending therebetween.

Another embodiment of a roller bearing assembly, in accordance with thepresent disclosure, includes an inner cup defining a tapered innerraceway, an outer cup defining a tapered outer raceway, the taperedouter raceway having a convex profile, the convex profile being definedby an intersection of the outer tapered raceway and a central plane inwhich a longitudinal center axis of the roller bearing assembly lies, aroller retainer having an inner perimeter, an outer perimeter and afrustoconically shaped body extending therebetween, the body defining aplurality of roller pockets, and a plurality of straight rollersdisposed between the tapered inner cup and the tapered outer cup, eachstraight roller being disposed in a corresponding roller pocket of theroller retainer so that each straight roller is in rolling contact withthe inner tapered raceway and the outer tapered raceway, each straightroller having a first end face, a second end face and a cylindrical bodyextending therebetween.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendeddrawings, in which:

FIG. 1 is a cross-sectional view of a roller bearing assembly inaccordance with an embodiment of the present disclosure;

FIG. 2A is a partial top view of an outer cup and straight roller of theroller bearing assembly shown in FIG. 1 , wherein the straight roller isat rest;

FIG. 2B is a partial top view of an outer cup and straight roller of theroller bearing assembly shown in FIG. 1 , wherein the straight roller isin motion;

FIG. 3 is a partial view of the roller retainer and a correspondingstraight roller of the roller bearing assembly shown in FIG. 1 ;

FIG. 4 is a partial cross-sectional view of the roller bearing assemblyshown in FIG. 2A, taken along line 4-4;

FIG. 5 is a partial, cross-sectional view of the roller bearing assemblyshown in FIG. 2B, taken along lines 5-5;

FIG. 6 is an enlarged view of the indicated portion of thecross-sectional view of the roller bearing assembly shown in FIG. 1 ;

FIG. 7 is a partial cross-sectional view of a second embodiment of aroller bearing assembly in accordance with the present disclosure,wherein the straight roller is at rest;

FIG. 8 is a partial cross-sectional view of the second embodiment of aroller bearing assembly shown in FIG. 7 with the present disclosure,wherein the straight roller is in motion;

FIG. 9 is a cross-sectional view of a prior art roller bearing assembly;

FIG. 10A is a partial top view of an outer cup and a straight roller ofthe prior art roller bearing assembly shown in FIG. 9 , wherein thestraight roller is at rest;

FIG. 10B is a partial top view of an outer cup and a straight roller ofthe prior art roller bearing assembly shown in FIG. 9 , wherein thestraight roller is in motion;

FIG. 11 is a partial view of the roller retainer and a correspondingstraight roller of the prior art roller bearing assembly shown in FIG. 9; and

FIG. 12 is a partial cross-sectional view of the prior art rollerbearing assembly shown in FIG. 10B, taken along line 12-12.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention according to the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation,not limitation, of the invention. In fact, it will be apparent to thoseskilled in the art that modifications and variations can be made in thepresent invention without departing from the scope and spirit thereof.For instance, features illustrated or described as part of oneembodiment may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention covers suchmodifications and variations as come within the scope of the appendedclaims and their equivalents.

Referring now to the figures, as shown in FIGS. 1 and 6 , an embodimentof a roller bearing assembly 100 in accordance with the presentdisclosure includes a tapered inner cup 110, a tapered outer cup 130, aroller retainer 170 disposed therebetween that defines a plurality ofroller pockets 178, and a plurality of straight rollers 150, eachstraight roller being rotatably received in a corresponding rollerpocket 178. Roller retainer 170 and straight rollers 150 are rotatablyreceived between inner cup 110 and outer cup 130 such that each straightroller 150 is rotatably received between, and in rolling contact with,an inner raceway 118 and an outer raceway 138 defined by inner cup 110and outer cup 130, respectively. Note, although inner cup 110 and outercup 130, as shown, are constructed using drawn cup technology, inalternate embodiments the inner cup and the outer cup may be precisionground cups. Additionally, as shown in FIG. 1 , an inner collar 180defining a central shaft bore 182 is disposed radially inwardly of innercup 110 and an outer collar 184 is disposed radially outwardly of outercup 130, to facilitate installation of bearing assembly.

Referring now to FIG. 3 , in the embodiment shown, roller retainer 170includes an annular first end member 172, an annular second end member174, and a plurality of elongated central members 176 extendingtherebetween, thereby forming the plurality of roller pockets 178.Referring additionally to FIG. 1 , in that second end member 174 has agreater diameter than first end member 172, central members 176 extendbetween first end member 172 and second end member 174 in afrustoconical fashion. A straight roller 150 is rotatably received in acorresponding roller pocket 178, each straight roller 150 including afirst end face 152, a second end face 154, and a cylindrical bodyextending therebetween. The dimensions of roller pockets 178 of rollerretainer 170 are selected to limit the extent to which eachcorresponding straight roller 150 is allowed to rotate about itscorresponding pivot axis 160 (FIG. 1 ), as inner cup 110 and outer cup130 rotate relative to each other, as discussed in greater detail below.Note, the dimensions of roller pocket 178 as shown in FIG. 3 areexaggerated, as is the extent to which straight roller 150 is able torotate therein, for illustrative purposes only.

As best seen in FIG. 6 , inner cup 110 includes an annular inner flange112, and annular outer flange 114, and a frustoconically shaped body 116extending therebetween. The frustoconically shaped inner surface of body116 is adjacent inner collar 180, whereas the frustoconically shapedouter surface of body 116 defines inner raceway 118 of roller bearingassembly 100. Similarly, outer cup 130 includes an annular inner flange132, an annular outer flange 134, and a frustoconically shaped body 136extending therebetween. As well, the frustoconically shaped outersurface of body 136 is adjacent outer collar 184. Note, however, outerraceway 138 of bearing assembly 100, which is defined by the innersurface of the outer cup's body 136, is not defined by frustoconicalsurface. Rather, outer raceway 138 defines a convex profile, as definedby the intersection of a plane of symmetry of rolling bearing assembly100, that being any plane in which a longitudinal center axis 101 of thebearing assembly lies, with outer raceway 138 of outer cup 130. As such,as shown in FIGS. 2A and 4 , when straight roller 150 is in the “atrest” position, that being when there is no relative motion betweeninner cup 110 and outer cup 130 and a longitudinal center axis 158 ofstraight roller 150 intersects longitudinal center axis 101 of rollerbearing assembly 100, straight roller 150 is in contact with innerraceway 118 along its entire length. However, due to the convex profileof outer raceway 138, straight roller 150 is only in contact with outerraceway along a portion of its full length, that being a middle portion.Similarly, inner raceway 118 may have a concave profile, as shown inFIG. 7 , defined by an intersection of the central plane and the innerraceway 118.

However, as relative rotation occurs between inner cup 110 and outer cup130, each straight roller 150 will begin to rotate about its pivot axis160 (FIG. 1 ) that is both transverse to its longitudinal center axis158 and extends outwardly from its midpoint to intersect longitudinalcenter axis 101 of the bearing assembly. This rotational motion aboutpivot axis 160 is best seen in FIGS. 2B and 5 . Note, the full extent towhich each straight roller 150 may rotate about its pivot axis 160 islimited by the dimensions of its corresponding roller pocket 178, asshown in FIG. 3 . As previously noted, the rotation of each straightroller 150 about its corresponding pivot axis 160 is due to the factthat its first end face 152 does not have as far to travel along outerraceway 138 as does its second end face 154. For example, as shown inFIG. 2B, for straight roller 150 not to rotate about its pivot axis 160,second end face 154 would have to roll along “fast path” 142 of racewayfaster than first end face 152 rolled along “slow path” 144 since fastpath 142 is a larger circular path than is slow path 144. Of course,this is not possible as all portions of straight roller 20 rollsimultaneously. “Neutral path” 146 represents the path that the midpointof each straight roller 20 travels along outer raceway 138.

Referring now to FIGS. 2B and 5 , unlike the previously discussed priorart bearing assembly 10 shown in FIGS. 9 through 12 , the rotation ofeach straight roller 150 about its pivot axis 160 causes convex outerraceway 130 to now function as though it has a straight profile withrespect to longitudinal center axis 158 of the straight roller.Specifically, the middle portion of each straight roller 150 of thedisclosed roller bearing assembly 100 maintains contact with outerraceway 138 as the straight roller rotates about its pivot axis 160,whereas the middle portion of each straight roller 20 in the prior artbearing assembly loses contact with outer raceway 18, resulting in theend loading of the rollers. As such, as the rotation of the disclosedstraight rollers 150 causes their end portions to come into contact withouter raceway 138, an even greater portion of each straight roller 150is in contact with outer raceway 138 than when the straight rollers arein the at rest position shown in FIGS. 2A and 4 . Therefore, the convexouter raceway 138 of the disclosed bearing assembly 100 leads to reducedend loading of straight rollers and, therefore, reduced spalling.

While one or more preferred embodiments of the invention are describedabove, it should be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope and spirit thereof. It is intended thatthe present invention cover such modifications and variations as comewithin the scope and spirit of the appended claims and theirequivalents.

The invention claimed is:
 1. A roller bearing assembly comprising: atapered inner cup defining an inner raceway having a concave profile,the concave profile defined by an intersection of the central plane andthe inner raceway; a tapered outer cup defining an outer raceway, theouter raceway having a convex profile, the convex profile being definedby an intersection of the outer raceway and a central plane in which alongitudinal center axis of the roller bearing assembly lies, thetapered outer and inner cups being concentric about the longitudinalcenter axis; a plurality of straight rollers disposed between thetapered inner cup and the tapered outer cup so that each straight rolleris in rolling contact with the inner raceway and the outer raceway, eachstraight roller having a first end face, a second end face and acylindrical body extending therebetween; and a roller retainer defininga plurality of roller pockets, each roller pocket receiving acorresponding straight roller, and each roller pocket being symmetricaland having dimensions so that each straight roller is limitedlyrotatable in both directions about a pivot axis that intersects thelongitudinal center axis of the roller bearing assembly and a midpointof the longitudinal center axis of the corresponding straight roller,wherein the pivot axis is transverse to the longitudinal center axis ofthe corresponding straight roller.
 2. The roller bearing assembly ofclaim 1, wherein the tapered inner cup and the tapered outer cup furthercomprise drawn cups.
 3. A roller bearing assembly, comprising an innercup defining a tapered inner raceway having a concave profile, theconcave profile defined by an intersection of the central plane and theinner raceway; an outer cup defining a tapered outer raceway, thetapered outer raceway having a convex profile, the convex profile beingdefined by an intersection of the outer tapered raceway and a centralplane in which a longitudinal center axis of the roller bearing assemblylies, the outer and inner cups being concentric about the longitudinalcenter axis; a roller retainer having an inner perimeter, an outerperimeter and a frustoconically shaped body extending therebetween, thebody defining a plurality of roller pockets; and a plurality of straightrollers disposed between the tapered inner cup and the tapered outercup, each straight roller being disposed in a corresponding rollerpocket of the roller retainer so that each straight roller is in rollingcontact with the inner tapered raceway and the outer tapered raceway,each straight roller having a first end face, a second end face and acylindrical body extending therebetween, wherein each roller pocket issymmetrical and has a maximum width that is greater than a maximum widthof each corresponding straight roller so that each straight roller islimitedly rotatable in both directions about a pivot axis thatintersects the longitudinal center axis of the roller bearing assemblyand a midpoint of the longitudinal center axis of the correspondingstraight roller, wherein the pivot axis is transverse to thelongitudinal center axis of the corresponding straight roller.
 4. Theroller bearing assembly of claim 3, wherein the inner and the outer cupsfurther comprise drawn cups.